Materials

nventor and professional engineer has, until recently, been deemed too difficult Geir Jensen has a passion for devising and so generally ignored. Instead, research practical solutions to problems. Through has focused on the parts of buildings that collaborations with scientists and the lend themselves more favourably to fire- exploitation of opportunities as and when resistance measures. As a result, a lot of time they arise, Jensen has recently brought to and money has been invested in installing Ifruition an idea first envisioned 20 years ago. fire-resistance techologies in buildings which From idea to reality, the story of Jensen’s remain vulnerable to fire (due to the presence invention is an inspiring example of how far of unprotected openings like vents and gaps). you can get with limited resources, as long as In addition, there is a lack of standardised you have sufficient vision and ambition. testing in this area, making it difficult for those requiring fire-resistance measures to make CONFLICTING INTERESTS informed decisions. The challenge of designing buildings to withstand fire is an ongoing issue for FILLING THE GAP the construction industry. In many cases, There currently exists a range of methods buildings, in particular their exterior for making ventilation gaps fire resistant. construction, also need to be ventilated to Intumescent materials that expand on prevent rot and fungus. However, in practical exposure to flames and hot smoke gases construction, ventilation and fire resistance create a seal against the spread of fire. are contradictory requirements: to ventilate a However, these take a few minutes to fully building you need gaps through which air can seal, so still allow fire to spread in the critical freely pass, but these gaps present a major early stages. An alternative technology, flame area of weakness in the fire resistance of a arresters, uses the principle of a quenching How new building. distance to prevent combustion. However, they have a very short working duration of a This conundrum has for a long time been a few milliseconds up to a few seconds. major challenge to both research scientists and the construction industry. The question Evidently, even a combination of these two technology of how to make ventilation gaps fire resistant technologies would leave a significant time gap during which fire could spread through a building. Fascinated by this challenge, Geir Jensen's Jensen has spent the last 20 years designing and refining an invention which is set to is stopping fire research and revolutionise the world of fire resistance. inventions are FROM IDEA TO REALITY The story of Jensen’s invention begins in 1994, paving the way when he observed the construction of the for a new mode Eidsvoll 1814, the constitutional building of in its tracks Norway. The building contained many vertical After spotting an existing weakness in fire prevention of thinking about ventilation shafts and Jensen was struck by methods, Geir Jensen, Technical Director at COWI the potential fire threat posed by these shafts Fire International, has spent the last twenty years fire resistance and the lack of methods to prevent fires researching and developing new ways to stop the spread of fire.

Left: Over 20 years, cavity fire barriers for exterior construction evolved from the early types that performed only after being sealed by fire (flame and embers could penetate for the first few minutes). Middle: Perforated or labyrinth-type flame arrestors would block fire for the first five minutes, not after, and ventilated less efficiently. Right: The result is well ventilating malleable barriers for gaps or cracks of any size or form. These stand up to embers and direct flame as well as sustained fire, instantly at zero hours and for hours. (Coloured drawings by B Østman et al)

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spreading. This single observation prompted Jensen’s interest and research in this area and Detail sparked a thought which has since proven to be revolutionary in this field. RESEARCH OBJECTIVES Geir Jensen’s research focuses on Motivated by a request for research from Your patented technology combines sheet labyrinths to block flame, mesh to preventing the spread of fires through the authorities and academia, in 1998 Jensen the commonly used principles of block embers etc. This new technology design and manufacture of specialised air conducted a review of available mechanisms intumescence and quenching diameter simplified all this. vents for use in the construction industry. to prevent fire spreading through vents. This with a heat sink material. How does review gave him the idea of combining current the heat sink work to prevent the What effect has your research had on FUNDING technologies with new thinking to develop a spread of fire? testing and standards in this field? Innovation Norway unique and more effective method. Jensen's The function of the heat sink is to delay My research and the ensuing technology new technology, Firebreather, combines Flame contact ignites heating of the unexposed side while the has proven that “open state fire COLLABORATORS flame arresters and intumescent materials combustibles in just one vent is still in the open state. Temperature resistance” is technically feasible. • Turid Buvik, Innovation Norway to three seconds. New test with a third component that acts as a heat methods had to be designed must be kept below the ignition threshold Therefore, it was decided in North • Amal Tamim, COWI Gulf (now at sink. The heat sink material efficiently lowers in the USA and Europe in of the gas emitted by the fire source. America to dedicate a new test method Arencon, Canada) the smoke gas temperature to below the order to test whether vents for direct flame impingement of open • Phil Grimwood, Cambridge Fire instantly block flame attacks ignition temperature of fuels, stemming the while they are still fully open What fire scenarios should prevention state elements (vented construction) Research (now Technical Director of initial transfer of flames until the intumescent methods be tested for? during the zero- to five-minute period. Dixon International Group) material becomes effective. This way, fire Until this invention, no ventilation fire This became the ASTM E2912 Standard. cannot penetrate at any time from the exact dampers or air transfer grilles or other The test method for vents exposed BIO moment the fire exposure starts (zero hours) vented construction parts had been to wildfire adopted that method, Geir Jensen is a Technical up to several hours later. This is key – all In terms of fire, a few seconds can tested for fire resistance during the first ASTM E2886. In Europe CEN Director of Fire Protection at products are assessed on a time scale but five minutes after fire ignition. That was decided to add a similar method multi-disciplinary consulting it begins five minutes after ignition; that make all the difference and, ultimately, because, conventionally, fire resistance to both new prEN 1364-5 and group COWI. He is also an seemingly small window of the first five elements of buildings are inherently prEN 1364-6 Standards. In France a inventor and is particularly minutes is a crucial period when flames and by providing instant and lasting homogenous and airtight, so if an object guide has been issued that explains interested in designing embers could still be passing through other resisted fire at five minutes it could be how to apply open state fire resistance fire resistant solutions for the products. protection, Jensen’s inventions buy the assumed it would have done so for the vents in facades (my technology) and construction industry. time to reduce damage and loss previous five minutes as well, so no need refers to ASTM 2912 (Bois construction Over the next few years, Norwegian to test that initial period. In addition, the et propagation du feu par les façades En CONTACT government funding allowed for prototype fire test furnaces require some minutes to application de l’Instruction Technique Geir Jensen development. Prototype testing in 2002 malleable vent to seal irregular gaps and are paving the way for a new mode of thinking run correctly and have been used as an 249 01/02/2017). Technical Director Fire Engineering proved highly successful, providing both cracks. The vent can easily be installed by about fire resistance. His vision, ambition excuse to not register failures at zero to Cowi AS immense satisfaction and the motivation to hand and is a fully reversible design, allowing and perseverance have resulted in unique five minutes. You have been working on hypoxic Trondheim progress the design. Between 2002 and 2004 it to be installed and removed without leaving new methods to stop fire from spreading (low oxygen) air technology for fire Norway Jensen worked on refining his design and a trace. This feature makes it particularly through vents. These effective, affordable Fire dampers have always been tested prevention. What are the limitations of manufacturing an eave vent. 2004 marked appealing for use in heritage buildings. With and easy-to-install technologies protect not as open from the start and they could this method? T: +47 02694 a significant milestone in progress, as the a patent application in progress, Jensen’s only the structure itself, but also prevent the not prevent fire spread during the first A constant low-oxygen indoor climate +47 907 83 007 invention was published as a poster paper at inventions are continuing to change long fire spreading to neighbouring buildings. In minutes before they closed. All fire that is fire preventative but occupiable E: [email protected] the annual Interflam conference. standing views on fire protection methods. terms of fire, a few seconds can make all the dampers would therefore fail if tested is a very simple and clean method. W: www.cowi.com difference and, ultimately, by providing instant from ‘zero hours’. So, the industry has Except, the more that the low oxygen Although faced at times with a lack of PREVENTION IS KEY and lasting protection, Jensen’s inventions are continued to test dampers as if they were air leaks out and must be replaced, interest and resistance from industry Clearly, Geir Jensen's research and inventions buying the time to reduce damage and loss. solid objects, i.e., failures are registered the more energy is required to refill. competitors, Jensen persevered with his from five minutes onwards only. So, leaky rooms are ruled out. Low vision. In the subsequent years, he filed oxygen for occupation does not work patent applications, created building guides This delay in the testing is also partly for combustibles with very low ignition Height of ented caity barrier of and handbooks, and addressed the lack fire spread perforated metal type due to the idea that fires take some thresholds, as then the oxygen content of test standards. In a review of vented fire fire spread delayed time to build up in rooms so usually do in the room becomes so low it is No caity barrier or barrier fails barriers in 2013, Jensen brought to light to preent entry of embers or not penetrate that early. This is valid uninhabitable. the lack of appropriate, comprehensive flame before it is sealed New standards verify for most indoor fires, though there are whether ventilating tests. In his review, Jensen states that most cavity barriers in gaps exemptions. For exterior fires, however, What are your aspirations for 2017 and current tests do not adequately simulate 5m ented caity or cracks resist flame wind-driven embers and flames abound beyond? barrier of wooden and fire consistently likely fire scenarios, such as sudden flame. labyrinth type fire and penetrate vents in seconds without To see national codes require open state spread delayed through the open and The conclusion to his report suggests sealed states, i.e., from warning. All parties are agreed that fire resistant ventilation where applicable, re-developing an existing full-scale test to zero hours for as long conventional vents were not acceptable. world-wide. Also, to see progress of my ented caity barriers rated for as the fire partition time include exposure from zero hours by direct fire resistance, embers and flame rating –green curve. This Before my invention, attempts were ideas on water mist and sprinklers for fire flame impingement. impingement during open and means they respond to made to close off vents manually if a fire protection. closed states fire as if they are airtight was getting near, or use vents of metal

masonry or gypsum walls Based on the success of his previous design, min Time Jensen is currently developing a linear

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